In a conventional communications mode (for example, a communications mode based on a cellular network), a terminal directly communicates with a network-side device in a network coverage area. An example in which a terminal 1 located within coverage of a cellular network communicates with a network-side device (for example, a base station (eNB)) is used. Before the terminal 1 reports a data packet to the eNB, the terminal 1 needs to initiate random access to the eNB by using an air interface and establish a connection to the eNB, and then reports the data packet to the eNB by using the connection to the eNB. Before the eNB delivers a data packet to the terminal 1, the eNB also needs to establish a connection to the terminal 1, and delivers the data packet to the terminal 1 by using the connection to the terminal 1.
It can be seen from the foregoing example that a terminal can communicate with a network-side device only when the terminal is located within network coverage. A terminal beyond the network coverage (for example, the terminal is located in a network coverage blind spot such as a stair corner) cannot communicate with the network-side device, and as a result, a normal communication service cannot be performed. The network-side device can only identify a process of communication with the terminal within the network coverage, but cannot identify communication performed with the terminal beyond the network coverage.